The invention relates to document reading devices in which an original document stacked on a document tray is transported on a document transport path to an output tray through a document reading area.
Document reading devices commonly used in image forming apparatuses automatically feed a plurality of original document sheets whose images are to be read consecutively, from a document tray to a document reading area. In such document reading devices, an original document to be fed to the document reading area is transported on a document transport path that is formed so as to lead from the document tray to a document platen.
Some of such document reading devices are provided with a document transport path that has an approximately C-shaped curve. The curve allows an original document to be fed to the document platen in an approximately horizontal position. Also, the curve contributes to downsizing of a document transport device. In the case, the document transport path has an upper portion, a curved portion, and a lower portion. Thus, it is impossible to remove an original document jammed in the lower portion even when a top cover of the document transport device is opened.
To deal with the foregoing problem, JP H11-5659 A discloses that a document holder, which holds an original document placed on the document platen so that the document will not move, is pivoted around a pivot axis that is oriented parallel to a document transport direction, to expose a portion of a document transport path positioned immediately above the document holder.
However, the prior art document holder needs to be pivoted at a wide angle for proper removal of an original document jammed in the document transport path. A small pivot angle of the document holder makes it hard to reach an original document jammed at a rear side of the document reading device, thereby preventing proper removal of the jammed document.
In view of the foregoing problem, document reading devices have been proposed in which a portion of a bottom surface thereof positioned immediately below a lower portion of the document transport path serves as a movable member that is pivotable around a pivot axis oriented in a direction perpendicular to a document transport direction. The movable member is pivoted to expose the whole length, in the direction perpendicular to the document transport direction, of the lower portion of the document transport path.
On the bottom surface of the document reading device, however, a document holder for pressing an original document against the document platen is provided so as to extend over the whole length and breadth of the document platen. The document holder is a white, flexible sheet that is positioned outwardly with respect to the movable member.
If the document holder is entirely fixed to the bottom surface, a portion of the document holder positioned immediately below the pivot axis of the movable member is folded when the movable member is pivoted. Repeated pivot movements of the movable member cause the portion to have such a fold as to prevent the portion from pressing an original document flat against the document platen. Thus, there is a space left between the document holder and the document platen or between the holder and the original document. The space allows a leak of light irradiated on the document for scanning an image thereof. The leak results in undesirable image noise on image data read from the document. Also, a portion of the document is prevented from being pressed flat against the document platen. Accordingly, image data cannot be precisely read from the document.
A feature of the invention is to provide a document reading device capable of reading an image of an original document precisely. The document reading device has a movable member that is pivoted to expose a portion of a document transport path and a document holder that is positioned outwardly with respect to the movable member. The document holder is configured so as not to have a fold even after repeated pivot movements of the movable member. The configuration prevents undesirable image noise from appearing on image data read from an original document. Also, the configuration allows an original document to be pressed flat against the document platen.